MATLAB Compiler

Optimizing Loops

Simple Indexing

(array_indexing) This optimization improves the performance of simple one- and two-dimensional array index expressions. Without this optimization, all array indexing uses the fully general array indexing function, which is not optimized for one- and two-dimensional indexing. With this optimization enabled, indexing uses faster routines that are optimized for simple indexing. For example,

function y = test(x,i1,i2);
y = x(i1,i2);

If you compile this with the -O none option, you get

...
mlfAssign(
  &y,
  mlfIndexRef(mclVsa(x, "x"), "(?,?)", mclVsa(i1, "i1"),
              mclVsa(i2, "i2")));
...

Compiling with -O none -O array_indexing:on gives

...
mlfAssign(
  &y, mclArrayRef2(mclVsa(x, "x"), mclVsa(i1, "i1"),
                   mclVsa(i2,"i2")));
...

The mclArrayRef2 function is optimized for two-dimensional indexing. mclArrayRef1 is used for one-dimensional indexing.

Nonscalar Arrays

Loop Simplification